diff --git a/Makefile b/Makefile
index b9af7e4..6f1a82d 100644
--- a/Makefile
+++ b/Makefile
@@ -21,17 +21,12 @@ PATH_DOC_IMG=${PATH_DOC}/img
 PATH_MANUAL_TEXI=${PATH_DOC}/manual.texi
 
 src_js := index.js $(wildcard $(PATH_LIB)/*.js)
+src_tests := index.js $(wildcard $(PATH_TEST)/test-*)
 doc_src := $(wildcard $(PATH_DOC)/*.texi)
 doc_imgs := $(patsubst %.dia, %.png, $(wildcard $(PATH_DOC_IMG)/*.dia))
 
 COMBINE=${PATH_TOOLS}/combine
 
-TESTS := $(shell find "$(PATH_TEST)" \
-	-name 'test-*' \
-	-a ! -name 'test-combine*.js'\
-)
-TEST_COMBINE := $(PATH_TEST)/test-combine*.js
-
 
 .PHONY: combine doc test test-combine
 
@@ -51,19 +46,15 @@ mkbuild-doc: $(PATH_DOC_OUTPUT)
 # browser)
 $(PATH_COMBINE_OUTPUT): $(src_js) | mkbuild
 	${COMBINE} > "$(PATH_COMBINE_OUTPUT)"
-$(PATH_COMBINE_OUTPUT_FULL): $(src_js) | mkbuild
+$(PATH_COMBINE_OUTPUT_FULL): $(src_js) $(src_tests) | mkbuild
 	INC_TEST=1 "$(COMBINE)" > "${PATH_COMBINE_OUTPUT_FULL}"
 $(PATH_BUILD)/browser-test.html: $(PATH_COMBINE_OUTPUT_FULL)
 	cp "$(PATH_BROWSER_TEST)" "$(PATH_BUILD)"
 combine: $(PATH_COMBINE_OUTPUT) $(PATH_BUILD)/browser-test.html
 
-# run tests
-test: default $(TESTS) test-combine
-test-combine: default $(TEST_COMBINE)
-test-%.js: default
-	node $@
-test-%: default
-	./$@
+
+test:
+	$(MAKE) -C $(PATH_TEST)
 
 # performance tests
 perf: default $(PERF_TESTS)
diff --git a/test/Makefile b/test/Makefile
new file mode 100644
index 0000000..1a3e26b
--- /dev/null
+++ b/test/Makefile
@@ -0,0 +1,17 @@
+
+tests := $(shell find . \
+	-name 'test-*' \
+	-a ! -name 'test-combine*.js'\
+)
+tests_combine := test-combine*.js
+
+.PHONY: FORCE test test-combine
+
+
+default: $(tests) combine
+combine: $(tests_combine)
+
+test-%.js: FORCE
+	node $@
+test-%: FORCE
+	./$@